Shower handle part identification question

What is the name of the little screws that are used for securing that cover plate that goes around the shower handle stem covers? They install against the wall.

The screws are very small, have no head, and pointed at one end.

My wife installed new shower handle hardware, but left those screws out to install the next day and now they are missing. I need to know what they're called so I can pick up some replacements (if possible)